OSI Reference Model

OSI Model: OSI Stands for Open Systems Interconnect. Which is define how multiple device or different manufacturing device connect with each other. OSI Model Developed by ISO (International Organization for Standardization). OSI Model define 7 layers for communication.

SL	Layer Number	Layer Name
1	Layer 7	Application
2	Layer 6	Presentation
3	Layer 5	Session
4	Layer 4	Transport
5	Layer 3	Network
6	Layer 2	Data Link
7	Layer 1	Physical

Application Layer: Application Layer provides interface between User Interface and Network. Like an web page come to user for access. Application Layer Protocol is Telnet, FTP, HTTP etc.

Presentation Layer: Presentation Layer Controls data formatting and syntax. If Receiving Device not Understand Receiving Device Data. Then Presentation layer control the data conversation. Sometimes Presentation Layer encrypt and compress the data.

Session Layer: Session Layer is responsible for establishing, Maintaining and Terminating the sessions between devices. If session broken, this layer try to recover the session.

Transport Layer: Transport Layer responsible for data transfer. It's may be TCP or UDP. TCP is Connection-oriented and UDP is Connection less.

Connection-oriented protocols provide several important services: Segmentation and sequencing, Connection Establishment, Acknowledgement and Flow control

Network layer: Network Layer responsible for transporting data between networks. Network Layer major responsibilities is Logical Addressing and Routing. Network Layer Protocol is IP and IPX.

Data Link layer: Data Link Layer is responsible for transporting data within a network.

Physical layer: Physical Layer control the signaling and transferring of raw bits into physical medium.